Jamie suggested verifying that the problem is indeed with the disk and not with the controller, so I tried switching the original boot disk to Slot #1 (from Slot #0 where it normally resides), but the same problem persists - the green "OK" indicator light keeps flashing even in Slot #1, which was verified to be a working slot using the spare 2.5 inch disk. So I think it is reasonable to conclude that the problem is with the boot disk itself.

The disk is a Seagate Savvio 10K.2 146GB disk. The datasheet doesn't explicitly suggest any recovery options. But Table 24 on page 54 suggests that a blinking LED means that the disk is "spinning up or spinning down". Is this indicative of any particular failure moed? Any ideas on how to go about recovery? Is it even possible to access the data on the disk if it doesn't spin up to the nominal operating speed?

If we have a SATA/USB adapter, we can test if the disk is still responding or not. If it is still responding, can we probably salvage the files?
Chiara used to have a 2.5" disk that is connected via USB3. As far as I know, we have remote and local backup scripts running (TBC), we can borrow the USB/SATA interface from Chiara.

If the disk is completely gone, we need to rebuilt the disk according to Jamie, and I don't know how to do it. (Don't we have any spare copy?)

Seems like the connector on this particular disk is of the SAS variety (and not SATA). I'll ask Steve to order a SAS to USB cable. In the meantime I'm going to see if the people at Downs have something we can borrow.

I couldn't find an external docking setup for this SAS disk, seems like we need an actual controller in order to interface with it. Mike Pedraza in Downs had such a unit, so I took the disk over to him, but he wasn't able to interface with it in any way that allows us to get the data out. He wants to try switching out the logic board, for which we need an identical disk. We have only one such spare at the 40m that I could locate, but it is not clear to me whether this has any important data on it or not. It has "hda RTLinux" written on its front panel with a sharpie. Mike thinks we can back this up to another disk before trying anything, but he is going to try locating a spare in Downs first. If he is unsuccessful, I will take the spare from the 40m to him tomorrow, first to be backed up, and then for swapping out the logic board.

Chatting with Jamie and Koji, it looks like the options we have are:

1. Get the data from the old disk, copy it to a working one, and try and revert the original FB machine to its last working state. This assumes we can somehow transfer all the data from the old disk to a working one.
2. Prepare a fresh boot disk, load the old FB daqd code (which is backed up on Chiara) onto it, and try and get that working. But Jamie isn't very optimistic of this working, because of possible conflicts between the code and any current OS we would install.
3. Get FB1 working. Jamie is looking into this right now.

I just want to mention that the situation is actually much more dire than we originally thought.  The diskless NFS root filesystem for all the front-ends was on that fb disk.  If we can't recover it we'll have to rebuilt the front end OS as well.

As of right now none of the front ends are accessible, since obviously their root filesystem has disappeared.

[jamie, gautam]

Today morning, the disks from LLO arrived. Jamie and I have been trying to get things back up and running, but have not had much success today. Here is a summary of what we tried.

Keith Thorne sent us two disks: one has the daqd code and the second is the boot disk for the FE machines. Since Jamie managed to successfully compile the daqd code on FB1 yesterday, we decided to try the following: mount the boot disk KT sent us (using a SATA/USB adapter) on /mnt on FB1, get the FEs booted up, and restart the RT models. 

While on FB1, Jamie realized he actually had a copy of the /diskless/root directory, which is the NFS filesystem for the FEs, on FB1. So we decided to try and boot some of the FEs with this (instead of starting from scratch with the disks KT sent us). The way things were set up, the FEs were querying the FB machine as the DHCP server. But today, we followed the instructions here to get the FEs to get their IP address from chiara instead. We also added the line 

/diskless/root *(sync,rw,no_root_squash,no_all_squash,no_subtree_check)

to /etc/exports followed by exportfs -ra on FB1. At which point the FE machine we were testing (c1lsc) was able to boot up. 

However, it looks like the NFS filesystem isn't being mounted correctly, for reasons unknown. We commented out some of the rtcds related lines in /etc/rc.local because they were causing a whole bunch of errors at boot (the lines that were touched have been tagged with today's date).

So in summary, the status as of now is:

1. Front-end machines are able to boot
2. There seems to be some problem during the boot process, leading to the NFS file system not being correctly mounted. The closest related thing I could find from an elog search is this entry, but I think we are facing a different probelm.
3. We wanted to see if we could start the realtime models (but without daqd for now), but we weren't even able to get that far today.

We will resume recovery efforts on Monday.

Summary:

I've been working on improving the 40m FINESSE model I set up sometime last year (where the goal was to model various RC folding mirror scenarios). Specifically, I wanted to get the locking feature of FINESSE working, and also simulate the DRMI (no arms) configuration, which is what I have been working on locking the real IFO to. This elog is a summary of what I have from the last few days of working on this.

Model details:

• No IMC included for now.
• Core optics R and T from the 40m wiki page.
• Cavity lengths are the "ideal" ones - see the attached ipynb for the values used.
• RF modulation depths from here. But for now, the relative phase between f1 and f2 at the EOM is set to 0.
• I've not included flipped folding mirrors - instead, I put a loss of 0.5% on PR3 and SR3 in the model to account for the AR surface of these optics being inside the RCs. 
• I've made the AR surfaces of all optics FINESSE "beamsplitters" - there was some discussion on the FINESSE mattermost channel about how not doing this can lead to slightly inaccurate results, so I've tried to be more careful in this respect.
• I'm using "maxtem 1" in my FINESSE file, which means TEM_mn modes up to (m+n=1) are taken into account - setting this to 0 makes it a plane wave model. This parameter can significantly increase the computational time. 

Model validation:

• As a first check, I made the PRM and SRM transparent, and used the in-built routines in FINESSE to mode-match the input beam to the arm cavities.
• I then scanned one arm cavity about a resonance, and compared the transmisison profile to the analytical FP cavity expression - agreement was good.
• Next, I wanted to get a sensing matrix for the DRMI (no arms) configuration (see attached ipynb notebook).
  • First, I make the ETMs in the model transparent
  • I started with the phases for the BS, PRM and SRM set to their "naive" values of 0, 0 and 90 (for the standard DRMI configuration)
  • I then scanned these optics around, used various PDs to look at the points where appropriate circulating fields reached their maximum values, and updated the phase of the optic with these values.
  • Next, I set the demod phase of various RFPDs such that the PDH error signal is entirely in one quadrature. I use the RFPDs in pairs, with demod phases separated by 90 degrees. I arbitrarily set the demod phase of the Q phase PD as 90 + phase of I phase PD. I also tried to mimic the RFPD-IFO DoF pairing that we use for the actual IFO - so for example, PRCL is controlled by REFL11_I.
  • Confident that I was close enough to the ideal operating point, I then fed the error signals from these RFPDs to the "lock" routine in FINESSE. The manual recommends setting the locking loop gain to 1/optical gain, which is what I did.
  • The tunings for the BS and RMs in the attached kat file are the result of this tuning.
  • For the actual sensing matrix, I moved each of PRM, BS and SRM +/-5 degrees (~15nm) around each resonance. I then computed the numerical derivative around the zero crossing of each RFPD signal, and then plotted all of this in some RADAR plots - see Attachment #1.

Explanation of Attachments and Discussion:

• Attachment #1 - Computed sensing matrix from this model. Compare to an actual measurement, for example here - the relative angle between the sensing matrix elements dont exactly line up with what is measured. EQ suggested today that I should look into tuning the relative phase between the RF frequencies at the EOM. Nevertheless, I tried comparing the magnitudes of the MICH sensing element in AS55 Q - the model tells me that it should be ~7.8*10^5 W/m. In this elog, I measured it to be 2.37*10^5 W/m. On the AS table, there is a 50-50 BS splitting the light between the AS55 and AS110 photodiodes which is not accounted for in the model. Factoring this in, along with the fact that there are 6 in-vaccuum steering mirrors (assume 98% reflectivity for these), 3 in air steering mirrors, and the window, the sensing matrix element from the model starts to be in the same ballpark as the measurement, at ~3*10^5 W/m. So the model isn't giving completely crazy results.
• Attachment #2 - Example of the signals at various RFPDs in response to sweeping the PRM around its resonance. To be compared with actual IFO data. Teal lines are the "I" phase, and orange lines are "Q" phase.
• Attachment #3 - FINESSE kat file and the IPython notebook I used to make these plots. 
• Next steps
  • More validation against measurements from the actual IFO.
  • Try and resolve differences between modeled and measured sensing matrices.
  • Get locking working with full IFO - there was a discussion on the mattermost thread about sequential/parallel locking some time ago, I need to dig that up to see what is the right way to get this going. Probably the DRMI operating point will also change, because of the complex reflectivities of the arm cavities seen by the RF sidebands (this effect is not present in the current configuration where I've made the ETMs transparent).

GV Edit: EQ pointed out that my method of taking the slope of the error signal to compute the sensing element isn't the most robust - it relies on choosing points to compute the slope that are close enough to the zero crossing and also well within the linear region of the error signal. Instead, FINESSE allows this computation to be done as we do in the real IFO - apply an excitation at a given frequency to an optic and look at the twice-demodulated output of the relevant RFPD (e.g. for PRCL sensing element in the 1f DRMI configuration, drive PRM and demodulate REFL11 at 11MHz and the drive frequenct). Attachment #4 is the sensing matrix recomputed in this way - in this case, it produces almost identical results as the slope method, but I think the double-demod technique is better in that you don't have to worry about selecting points for computing the slope etc. 

About 3.5 hours ago, all the PSL wall StripTool traces "flatlined", as happens when we had the EPICS freezes in the past - except that all these traces were flat for more than 3 hours. I checked that the c1psl slow machine responded to ping, and I could also telnet into it. I tried opening the StripTool on pianosa and all the traces were responsive. So I simply re-started the PSL StripTool on zita. All traces look responsive now.

The PMC was unlocked when I came in ~10mins ago. The wall StripTool traces suggest it has been this way for > 8hours. I was unable to get the PMC to re-lock by using the PMC MEDM screen. The c1psl slow machine responded to ping, and I could also telnet into it. But despite burt-restoring c1psl, I could not get the PMC to lock. So I re-started c1psl by keying the crate, and then burt-restored the EPICS values again. This seems to have done the trick. Both the PMC and IMC are now locked.

Unrelated to this work: It looks like some/all of the FE models were re-started. The x3 gain on the coil outputs of the 2 ITMs and BS, which I had manually engaged when I re-aligned the IFO on Monday, were off, and in general, the IMC and IFO alignment seem much worse now than it was yesterday. I will do the re-alignment later as I'm not planning to use the IFO today.

This was me.  I restarted the front ends when I was getting the MX streams working yesterday.  I'll try to me more conscientious about logging front end restarts.

[Nikhil, gautam]

We repeated the test that EricQ detailed here today. We have downloaded ~10min of data (between GPS times 11885925523 - 11885926117), and Nikhil will analyze it.

These are not the angular test parameters that we're looking for:

 recall that what we want is the low frequency beam spot variations and the feedback to be limited to a small high frequency band.

e.g. only inject noise at 40-50 Hz, not loud enough to find at 2x the injected frequency.

It should NOT be the case that the high frequency injected noise be dominating the RMS.

The coupling should be ~1e-3; some combination of beam spot mis-centering and beam spot motion.

I have replaced the old 11n wifi router (CISCO / Linksys) for the GC network with a new one with 11ac technology.

The new one is a 3band wifi router. Thus it has one 2.4GHz (11n) SSID and two 5GHz (11ac) SSIDs. All these have been set to be hidden. Just come to the 40m and find the necessary info for the connection.

Note that the user id / password for the admin tool have been changed from the default values.

It can look back 7 days trends now. There is still no vacuum channels. I can bring back the channels through the restore directory, but there are no data.

BL-FS300C-PH-LE was replaced after 2,904 hrs  It did not explode this time.  The 4 monts life period is actually pritty good because this is a $73.  cheap bulb. The best-high priced warranty is 5 months.

PS: future option_bulbless laser projector

HITACHI LP-WU3500 PROJECTOR	$2,549.00	
DLP, WUXGA, 3500 LUMENS, HDMI, 20K HR LASER, 5YR WARRANTY, 1.36-2.34:1 LENS, 24/7 DUTY CYCLE
45x72 IMAGE FROM 8' TO 13'10" LENS TO SCREEN, AND AT 10' APPROX. 154FL OF BRIGHTNESS ON A 1.0 GAIN SCREEN
http://www.projectorcentral.com/pdf/projector_spec_9722.pdf

This would give you everything you are requesting, plus a lamp-less design and 5yr warranty.  Ground shipping would be free anywhere in the lower 48, and we would not charge sales tax on orders billing/shipping outside of AZ.  If you have any questions or if you would like to order... just let me know!

I'm not sure if this has something to do with the model restarts / new RCG, but while I was re-enabling the MC watchdogs, I noticed the RMS sensor voltage channels on ITMX hovering around ~100mV, even though local damping was on (in which configuration I would expect <1mV if everything is working normally).  I was confused by this behaviour, and after staring at the ITMX suspension screen for a while, I noticed that the input to the "ASCP" and "ASCY" servos were "-nan", and the outputs were 10^20 cts  (see Attachment #1).

Digging a little deeper, I found that the same problem existed on ITMY, ETMX, ETMY, PRM (but not BS or SRM) - reasons unknown for now.

I have to check where this signal is coming from, but for now I just turned the "ASC Input" switch off. More investigation to be done, but in the meantime, ASS dither alignment may not be possible.

After consulting with Jamie, I have just disabled all outputs to the suspensions other than local damping loop outputs. I need to figure out how to get this configuration into the safe.snap file such that until we are sure of what is going on, the models start up in this safer configuration.

gedit 28 Oct 0026: Seems like this problem is seen at the sites as well. I wonder if the problem is related.

I spent some time today trying to debug this issue.

Jamie and I had opened up the c1sus frontend to try and replace the RFM card before we realized that the problem was in the RCG code generator. During this process, we had disconnected all of the back-panel cabling to this machine (2 ethernet cables, dolphin cable, and RFM cables/fibers). I thought I may have accidentally returned the cables to the wrong positions - but all the status indicator lights indicate that everything is working as it should, and I also confirmed that the cabling is as it is in the pictures of the rack on the wiki page.

Looking at the SimuLink model diagram (see Attachment #1 for example), it looks like (at least some of) these channels are actually on the dolphin network, and not the RFM network (with which we were experiencing problems). This suggests that the problem is something deeper. Although I did see nans in some of the ETMX ASC channels as well, for which the channels are piped over the RFM network. Even more puzzling is that the ASC MEDM screen (Attachment #3) and the SimuLink diagram (Attachment #2) suggest that there is an output matrix in between the input signals and the output angular control signals to the suspensions. As Attachment #4 shows, the rows corresponding to ITMX PIT and YAW are zero (I confirmed using z read <matrixElement>). Attachment #3 shows that the output of all the servo banks except CARM_YAW is zero, but CARM_YAW has no matrix element going to the ITMs (also confirmed with z read <servoOutputChannel>). So 0 x 0 should be 0, but for some reason the model doesn't give this output?

GV Edit: As EricQ just pointed out to me, nan x 0 is still nan, which probably explains the whole issue. Poking a little further, it seems like this is an SDF issue - the SDF table isn't able to catch differences for this hold output channel.

As I was writing this elog, I noticed that, as mentioned above, the CARM_YAW output was "nan". When I restart the model (thankfully this didn't crash c1lsc!), it seems to default to this state. Opening up the filter module, I saw that the "hold output" was enabled.

Toggling that switch made the nans in all the SUS ASC channels disappear. Mysterious .

All the points above stand - CARM_YAW output shouldn't have been going anywhere as per the output matrix, but it seems to have been responsible? Seems like a bug in any case if a model restarts with a field as "nan".

Anyways the problem seems to have been resolved so I'm going to try locking and dither aligning the arms now.

Rolf mentioned that a simple update could fix several of the CDS issues we are facing (e.g. inability to open up testpoints), but he didn't seem to have any insight into this particular issue. Jamie will try and recompile all the models and then we have to see if that fixes the remaining problems.

There are three methods we (will soon) have available to evaluate the round-trip dissipative losses in the arms that do not suffer from the ITM loss dominance:

• DC reflection method:
  • Compare reflected light levels from [ITM only] vs [arm cavity on resonance]
• Basler CCDs:
  • Infer large (or small) angle scatter loss with calibrated CCDs
• Reflection ringdowns:
  • Need AS port light injection, principle is similar to DC method but better (?)

DCREFL

The DC method comparing reflectivities has been used in the past and is relatively easy to do. After the recent vacuum troubles the first step should be to re-perform these as CDS permits (needs some ASS functionality and of course the MC to behave). It wouldn't hurt to know the parameters this depends on, aka mode overlap and modulation depths with better certainty. Maybe the SURF scripts for mode-spectroscopy can be applied?

CCDs

With the new CCD cameras calibrated, pre-vent we can determine the magnitude of the large-angle scatter loss (assuming isotropic scatter) of ETMX and possibly ETMY. Can we look past ETMX/ETMY from the viewports? Then we can probably also look at the small angle scatter of ITMX and ITMY. If not, once we open one of the chambers there's the option of installing mirrors as close as possible to the main beam path. The easiest is probably to look at ITMX, since there is plenty of space in the XEND chamber, and the camera is already installed.

ASPORT

This requires a lot of up-front work. We decided to use the spare 200mW NPRO. It will be placed on the PSL table and injected into an optical fiber, which terminates on the AS table. The again free space beam there needs to be sort-of mode-matched into the SRC ("sort-of" because mode-spectroscopy). We want to be able to phaselock this secondary beam to the PSL with at least a couple kHz bandwidth and also completely extinguish the beam on time-scales of a few microseconds. We will likely need to purchase a few components that we can salvage from other labs, I'm still going through the inventory and will know more soon (more detailed post to follow). We need to settle for the polarization we want to send in from the back.

Tentative Schedule (aggressive)

Week Aug 21 - Aug 27:

• Update mode-overlap estimates
• Obtain current DC refl estimates
• Spatial profile of auxiliary NPRO
• Fiber setup concept; purchasing
• CCD software prep work

Week Aug 28 - Sep 3:

• Re-evaluate modulation indices if necessary
• Optical beat AS Port Auxiliary Laser (ASAL) - PSL
• PLL setup
• CCD large angle prep work

Week Sep 4 - Sep 10:

• PLL CDS integration
• Amplitude-modulation preparation
• CCD large angles

Week Sep 11 - Sep 17:

• Fiber-injection
• AS table preliminary mode-matching
• Faraday setup
• CCD small angle prep work

Week Sep 18 - Sep 24:

• ASAL amplitude switching
• CCD small angles

Week Sep 25 - Oct 1:

• AS port ringdowns

In case you want to use it, I had profiled the Lightwave NPRO sometime back, and we were even using it as the AUX X laser for a short period of time. 

As for using the AS laser for mode spectroscopy: don't we want to match the beam into the cavity as best as possible, and then use some technique to disturb the input mode (like the dental tooth scraper technique from Chris Mueller's thesis)? 

Johannes and I did an arm scan of the X arm today (arm controlled with ALS, monitoring IR transmission) - only 2 IR FSRs were scanned, but there should be sufficient information in there to extract the modulation depth and mode matching - can we use Kaustubh's/Naomi's code?. The Y arm ALS needs to be touched up so I don't have a Y arm scan yet. Note that to get a good arm scan measurement, the High Gain Thorlabs PD should be used as the transmission PD.

I surveyed the lab today to see what we may need to buy for the AS laser setup.

We have:

NPRO 200 mW + Driver

Faraday Isolator from cabinet

ISOMET Model 1201E: This is a free space AOM I found in the modulator cabinet. It needs to be driven at 40MHz (to be confirmed) with ~6W of electrical power. For a 500 micron beam it can allegedly achieve rise times of '93' [units not specified, could this be nanoseconds?]. I did not find a dedicated driver for it, however there was a 5W minicircuits amplifier ZHL-5W-1 in the RF cabinet and a switch ZSDR-230, which has a typical switch time of 2 microseconds, however I'm not sure how this translates to rise/fall times of the deflected power. It seems we have everything to set this up, so we'll by the end of the week if we can use a combination of these things or if we need to buy additional driver electronics.

New Focus model 4004 broadband phase modulator which is labeled as dusty, and in fact quite dirty when looking through. We should attempt to clean this thing and maybe we can use it here or at the ends.

Probably all the optics we need for the PSL table setup.

We need:

Beat PD: How about one of these: EOT ET-3000A? I didn't find a broadband PD for the beat with the PSL

Fiber Stuff: coupler & polarization maintaining fiber 20m & collimator. There are a couple options here, which we can discuss in the meeting.

Faraday Isolator: If we want to inject P-polarization. If S is okay we can use a polarizing plate beamsplitter instead.

Possibly some large lenses for mode-matching to IFO (TBD)

Looks like MC1 got another big kick just under 4 hours ago. None of the other optics show any evidence of a glitch so it seems unlikely that this was some sort of global event. It's been well behaved for ~2weeks now. IMC was unlocked. I manually re-aligned MC1, at which point the autolocker was able to lock the IMC.

Looking at this plot, it seems that LR and UL coils seem to have the largest kicks. UR barely saw it. Not sure what (if anything) to make of this - apparently the optic moved by ~20urad with the UR magnet approximately the pivot.

A couple of minutes ago, Larry W swapped the fibers to our 40m Edgeswitch (BROCADE FWS 648G) to a faster connection. This is the switch to which our gateway machine, NODUS, is connected. The actual swap itself happened at the core router in Bridge, and took only a few seconds. After the switch, I double checked that I was able to ssh into nodus from my laptop, and Larry informed me that everything is working as expected on his end.

Larry also tells us that the other edgeswitch at the 40m (Foundry Networks), to which most of our GC network machines are connected, is a 100MBPS switch, and so we should re-route the connections from this switch to the BROCADE switch at our convenience to take advantage of the faster connection.

There was a pretty large glitch in MC1 about an hour ago. The misalignment was so large that the autolocker wasn't able to lock the IMC. I manually re-aligned MC1 using the bias sliders, and now IMC locks fine. Attached is a 90 second plot of 2K data from the OSEMs showing the glitch. Judging from the wall StripTool, the IMC was well behaved for ~4 hours before this glitch - there is no evidence of any sort of misalignment building up, judging from the WFS control signals.

Instock WIMA caps refilled to a minimum 50 pieces each.

This NPRO has a tripping power output******

" Hi Eric,

I checked with the Engineer as Vincent is travelling.

“The lasers have serial number below 2000 which we cannot repair them, we only can repair NPRO laser has serial number 2000 or later.”

Thanks,

Betty-Ann Watt

Last night, I collected ~30mins of data for the vertex seismometer channels and the POP QPD PIT/YAW signals with the PRMI locked on carrier (angular FF OFF). The ITM Oplev loops weren't DC coupled, as they are in the full IFO locking sequence, but I feel like the angular FF filters can be improved - there are frequent sharp dives in the AS110 signal level which are correlated with large amplitude motion of the POP spot on the control room CCD monitor.

Repeating the frequency domain multicoherence analysis using BS_X and BS_Y seismometer channels as witnesses suggest that we can win significantly (see Attachment #1).

I've never really implemented feedforward filters - I was planning on using ericq's latest entry on this subject as a guide. From what I gather, the procedure is as follows:

1. Pre-filter the target (POP QPD PIT or YAW) and witness (BS_X, BS_Y) channels
   • Downsample the 2k target data and 256Hz witness data to 32 Hz (how to choose this?)
   • Detrend (linear?)
   • Apply elliptic low pass filter (previously, a 3rd order Elliptic Low pass with 3dB ripple, 40dB stopband attenuation, corner at 5Hz was used).
2. Filter the target signal (i.e. POP QPD PIT/YAW) by the inverse actuator TF.
   • This "actuator TF" is a measurement of how actuating on the angular DoFs of the PRM affects the POP QPD spot.
   • So by pre-filtering the target signal through the inverse actuator TF, we get a measure of how much the PRM angular motion is.
   • The reason we want to do this is to give the FIR filter that produces optic motion (output) given ground motion sensed by the seismometer (input) fewer poles/zeros to fit (?).
   • The actual actuator TF has to be measured using DTT, and fit - is there anything critical about this fitting? Seems like this should be just a simple pendulum transfer function so a pair of complex poles should be sufficient?
3. The actual Wiener filter is calculated by the function miso_firlev.m. There are many versions of this floating around from what I can gather.
   • This function requires 3 input parameters.
     • Order of filter to be fit
     • Witness channels (can be multiple)
     • Target channel (has to be single, hence the "miso" in the function name).
   • Today, at the meeting, we talked about weighting the cost function that the optimal Wiener filter calculator minimizes.
   • The canonical wiener filter minimizes the mean squared error between the output of the filter and the desired signal profile (which for this particular problem is the angular motion of the PRM, calculated by dividing the target signal by the actuator TF, knowing which we can cancel it out).
   • But as seen in Attachment #1, the main reduction in RMS comes below f=5Hz.
   • So can we weight the cost function more heavily at lower frequencies? From what I can find in previous calculations, it looks like this weighting happens in the pre-filtering stage, which is not the same thing as including the frequency dependent weighting in the calculation of the Weiner filter? The PSD and acf are F.T. pairs per the Wiener-Khinchin theorem so intuitively I would think that weighting in the frequency domain corresponds to weighting on the lags at which the acf is calculated, but I need to think about this.
   • What kind of low-pass filter do we use to prevent noise injection at higher frequencies? Does the optimal filter calculation automatically roll-off the filter response at high frequencies?
4. As I write this, seems like there is another level of optimization of "meta-parameters" possible in this whole process - e.g. what is the optimal order of filter to fit? what is the optimal pre-filtering of training data? Not sure how much we can gain from this though.

Some notes from Rana from some years ago: https://nodus.ligo.caltech.edu:8081/40m/11519

If anyone has pointers / other considerations I should take into account, please post here.

There hasn't been a big glitch that misaligns MC1 by so much that the autolocker can't lock for at least 3 months, seems like there was one ~an hour ago.

I disabled autolocker and feedback to the PSL, manually aligned MC1 till the MC_REFL spot looked right on the CCD to me, and then re-engaged the autolocker, all seems to have gone smoothly.

Current objectives and statuses:

• CAD Model of 40m lab (facility, chambers, invacuum components etc)
  • Status: On hold since I'm unable to acquire general dimensions of 

40m Lab CAD

1. 40m_bldg.dwg has 2D drawing of the 40m building

• After importing file as a 2D sketch into solidworks, make sure to retrace all the lines before performing any 3D extrusion stuff.
• Made walls 3m high

2. 40m_VE.dwg has the Vaccuum Envelope.

• Divided the file into individual sketches for the tubes, test mass, and beam splitter chambers (so they can be individually modified later if required).

3. 40melev.dwg has the relative positioning between (1) and (2).

• Using this file to position objects inside building cad.

4. All files can be found in Dropbox folder [40m SOS Modeling], which should be renamed to [40m CAD].

5. Next step would be to add the optical table, mirrors.

Tip-Tilt Suspension

1. Current objective: (refer to D070172) - Increase the length of the side arms (so it matches the dimensions of D960001), while keeping the test mass subassembly at the same height.
2. Future objective: Resonant frequency FEM of the frame (sans the test mass), and then change height to get the desired frequency.

Past Work

• Completed solidworks model of SOS (D960001). I understand this is not the focus right now so this is for reference that the model is ready to be used.

Comments

• I will be in India from 16th December until 6th January so this is my final visit for this year. I have enough material to work from home, and will correspond with Koji over email regarding Lab CAD and tip-tilt suspension.

Gautam and I looked into the DAC noise contribution to the noise budget for homodyne detection at the 40m. DAC noise is currently the most likely limiting source of technical noise.

Several of us have previously looked into the optimal SRC detuning and homodyne angle to observe pondermotive squeezing at the 40m. The first attachment summarizes these investigations and shows the amount of squeezing below vacuum obtainable as a function of homodyne angle for an optimal SRC detuning including fundamental classical sources of noise (seismic, CTN, and suspension thermal). These calculations are done with an Optickle model. According to the calculations, it's possible to see 6 dBvac of squeezing around 100 Hz.

The second attachment shows the amount of squeezing obtainable including DAC noise as a function of current noise in the DAC electronics. These calculations are done at the optimal -0.45 deg SRC detuning and 97 deg homodyne angle. Estimates of this noise are computed as is done in elog 13146 and include de-whitening. It is not possible to observe squeezing with the current 400 Ω series resistor which corresponds to 30 pA/rtHz current noise at 100 Hz. We can get to 0 dBvac for current noise of around 10 pA/rtHz (1.2 kΩ series resistor) and can see 3 dBvac of squeezing with current noise of about 5 pA/rtHz at 100 Hz (2.5 kΩ series resistor). At this point it will be difficult to control the optics however.

So it seems reasonable to reduce the DAC noise to sufficient levels to observe squeezing, but we will need to think about the controls problem more.

Gautam and I redid our calculations, and the updated plot of squeezing as a function of DAC current noise per coil is shown in the attachment. The current noise is calculated as the maximum of the filtered DAC noise and the Johnson noise of the series resistor. The total noise is for four optics with four coils each.

The numbers are worse than we quoted before: according to these calculations we can get to 0 dBvac for current noise per coil of about 2.4 pA/rtHz at 100 Hz.

1. Should not count the ITMs. On those we can use big resistors / filters to cut out the noise.
2. For the initial LIGO, we used 7 K resistors and the mass was 10 kg. But...the output driver went +/- 150 V.

So we had a max F/m = (20 mA * 0.064 N/A)/(10 kg) = 0.0001. For the 40m, to get the same thing, we would need 40x less current (~0.5 mA). At the moment we have (12 V / 400 Ohm) = 30 mA.

We need to get a spectrum and times series of the required coil current for acquiring and holding the DRMI, and also the single arm. Then we can see where to make noise reductions to allow this drastic force reduction. 

Coil Driver Upgrade wiki here.

There was a power outage.

The IFO pressure is 12.8 mTorr-it and it is not pumped. V1 is still closed. TP1 is not running. The Rga is not powered.

The PSL output shutter is still closed. 2W Innolight turned on and manual beam block placed in its beampath.

3 AC units turned on at room temp 84F

1. I had to manually reboot c1lsc, c1sus and c1ioo.
2. I edited the line in /etc/rt.sh (specifically, on FB /diskless/root.jessie/etc/rt.sh) that lists models running on a given frontend, to exclude c1dnn and c1oaf, as these are the models that have been giving us most trouble on startup. After this, I was able to bring back all models on these three machines using rtcds restart --all. The original line in this file has just been commented out, and can be restored whenever we wish to do so.
3. mx_stream processes are showing failed status on all the frontends. As a result, the daqd processes are still not working. Usual debugging methods didn't work.
4. Restored all sus dampings.
5. Slow computers all seem to be responsive, so no action was required there.
6. Burtrestored c1psl to solve the "sticky slider" problem, relocked PMC. I didn't do anything further on the PSL table w.r.t. the manual beam block Steve has placed there till the vacuum situation returns to normal.

@Steve: I noticed that we are down to our final bottle of N2, not sure if it will last till 2 Jan which is presumably when the next delivery will come in. Since V1 is closed and the PSL beam is blocked, perhaps this doesn't matter.

from Steve: there are spare full N2 bottles at the south end outside and inside. I replaced the N2 on Sunday night. So the system should be Ok as is.

I also hard-rebooted megatron and optimus as these were unresponsive to ping.

*Seems like the mx_stream errors were due to the mx process not being started on FB. I could fix this by running sudo systemctl start mx on FB. After which I ran sudo systemctl restart daqd_*. But the DC errors persist - not sure how to fix this. Elogging suggests that "0x4000" errors are connected to timing problems on FB, but restarting the ntp service on FB (which is the suggested fix in said elogs) didn't fix it. Also unsure if mx process is supposed to automatically start on FB at startup.

Bulb  is replaced.

As mentioned in my previous elog, the CDS overview screen "DC" indicators are all RED (everything else is green). Opening up the displays for individual CPUs, the error message shown is "0x4000", which is indicative of some sort of timing error. Indeed, it seems to me that on the FB machine, the gpstime command shows a gps time that is ~1 second ahead of the times on other FE machines.

Running gpstime on other FE machines throws up an error, saying that it cannot connect to the network to update leap second data. Not sure what this is about...

I double checked the GPS timing module, we had some issues with this in the recent past. But judging by its front panel display, everything seems to be in order...

Rolf came here in the morning, but not sure what he did or if Jamie remotely did something. But the screen is green.

Just putting the relevant line from email from Rolf which at least identifies the problem here:

There still seems to be something funky with the X arm transmission PDs - I can't seem to get the triggering to switch between the QPD and the Thorlabs PD, and the QPD signal seems to be wildly fluctuating by several orders of magnitude from 0.01-100. The c1iscex FE was pulled out, and it seemed to me like someone was doing some cable re-arrangement at the X end.

I will look into this tomorrow. 

Mostly back to nominal operating conditions now.

1. EX TransMon QPD is not giving any sensible output. Seems like only one quadrant is problematic, see Attachment #1. I blame team EX_Acromag for bumping some cabling somewhere. In any case, I've disabled output of the QPD, and forced the LSC servo to always use the Thorlabs "High Gain" PD for now. Dither alignment servo for X arm does not work so well with this configuration - to be investigated.
2. BS Seismometer (Trillium) is still not giving any sensible output.
   • I looked under the can, the little spirit level on the seismometer is well centered.
   • I jiggled all the cabling to rule out any obvious loose connections - found none at the seismometer, or at the interface unit (labelled D1002694 on the front panel) in 1X5/1X6.
   • All 3 axes are giving outputs with DC values of a few hundred - I guess there could've been some big earthquake in early December which screwed the internal alignment of the sensing mass in the seismometer. I don't know how to fix this.
   • Attachment #2 = spectra for the 3 channels. Can't say they look very seismicy . I've assumed the units are in um/sec.
   • This is mainly bothering me in the short term because I can't use the angular feedforward on PRC alignment, which is usually quite helpful in DRMI locking.
   • But I think the PRM Oplev loop is actually poorly tuned, in which case perhaps the feedforward won't really be necessary once I touch that up.

What I did today (may have missed some minor stuff but I think this is all of it):

1. At EX:
   • Toggled power to Thorlabs trans monitoring PD, checked that it was actually powered, squished some cables in the e- rack.
   • Removed PDA55 in the green path (put there for EX laser AM/PM measurement). So green beam can now enter the X arm cavity.
   • Re-connected ALS cabling.
   • Turned on HV supply for EX Green PZT steering mirrors (this has to be done every time there is a power failure).
2. At ITMY table:
   • Removed temporary HeNe RIN/ Oplev sensing noise measurement setup. HeNe + 1" vis-coated steering mirror moved to SP table.
   • Turned on ITMY/SRM Oplev HeNe.
   • Undid changes on ITMY Oplev QPD and returned it to its original position.
   • Centered ITMY reflected beam on this QPD.
3. At vertex area
   • Looked under Trillium seismometer can - I've left the clamps undone for now while we debug this problem.
   • Power-cycled Trillium interface box.
   • Touched up PMC alignment.
4. Control room
   • Recover IFO alignment using combination of IR and Green beams.
   • Single arm locking recovered, dither alignment servos run to maximize arm transmission. Single arm locks holding for hours, that's good.
   • The X arm dither alignment isn't working so well, the transmission never quite hits 1 and it undergoes some low frequency (T~30secs) oscillations once the transmission reaches its peak value.
   • Had to do the usual ipcrm thing to get dataviewer to run on pianosa.

Next order of business:

1. Recover ALS:
   • aim is to replace the vertex area ALS signals derived from 532nm with their 1064nm counterparts.
   • Need to touch up end PDH servos, alignment/MM into arms, and into Fibers at ends etc.
   • Control the arms (with RMs misaligned) in the CARM/DARM basis using the revised ALS setup.
   • Make a noise budget - specifically, we are interested in how much actuation range is required to maintain DARM control in this config.
2. Recover DRMI locking
   • Continue NBing.
   • Do a statistical study of actuation range required for acquiring and maintaining DRMI locking.

After much googling, I figured out how to install pip on SL7:

Next, I installed git:

Turns out, actually, pip can be installed via yum using

1. 40m Lab CAD
   1. Worked further on positioning vacuum tubes and chambers in the building.
   2. Next step would be to find some drawings for optical table positions and vibration isolation stack. Need help with this! 
2. Tip Tilt Suspension (D070172)
   1. Increased the length of side arms. The overall height of D070172 assembly matches that of D960001.
   2. The files are present in dropbox in [40mShare] > [40m_cad_models] > [TT - Tip Tilt Suspension]

Status of the AS-port auxiliary laser injection

• Auxiliary laser with AOM setup exists, first order diffracted beam is coupled into fiber that leads to the AS table.
• There is a post-PMC picked-off beam available that is currently just dumped (see picture). I want to use it for a beat note with the auxiliary laser pre-AOM so we can phaselock the lasers and then fast-switch the phaselocked light on and off.
• I was going to use the ET3010 PD for the beat note unless someone else has plans for it.
• I obtained a fixed triple-aspheric-lens collimator which is supposed to have a very small M^2 value for the collimation on the AS table. I still have the PSL-lab beam profiler and will measure its output mode.
• Second attached picture shows the space on the AS table that we have for mode-matching into the IFO. Need to figure out the desired mode and how to merge the beams best.

40m CAD Project

1. All parts will be now named according to the numbering system in this excel sheet: LIGO 40m Parts List in dropbox folder [40mShare] > [40m_cad_models] > [40m Lab CAD]
2. I've placed optical tables in the chambers at 34.82" from the bottom for now. This was chosen by aligning the centre of test mass of SOS assembly (D960001) with that of vacuum tube (Steve however pointed out last week they might not necessarily be concentric).

Rendered the SOS assembly (D960001) with correct materials and all and it looks very nice. Will extend this to the building cad later.

I'm planning to construct a beat setup between the PSL and AUX beams. I am going to make it in the area shown in a blue square in the attached photo. This does not disturb Johannes' and PSL setups. The beams are obtained from the PBS reflection of the PSL and the dumped beam of the aux path (0th or 1st order beam of the AOM).

The beat setup has been made on the PSL table. The BS and the PD were setup. The beat was found at 29.42degC and 50.58degC for the PSL and AUX crystal temperatures, respectively.
We are ready for the EOM test. I have instruments stacked around the PSL table. Please leave them as they are for a while. If you need to move them, please contact with me. Thanks.

A picked-off PSL after the main modulator was used as the PSL beam. This was already introduced close to the setup thanks to the previous 3f cancellation test ELOG 11029. The AUX beam was obtained from the transmission of 90% mirror. Both paths have S polarization. The beams are combined with a S-pol 50% BS. The combined beam is detected by a new focus 1GHz PD.

The PSL crystal temp (actual) was 50.58degC. The AUX crystal temp was swept upward and the string beat was found at 50.58degC. After a bit of alignment, the beat strength was -18dBm (at 700V/A RF transimpedance of NF1611) .

Tip-Tilt Suspension CAD:
Discussed with Koji about motivation to simplify the design of this assembly, which has many unnecessary over-constraints. I have started to cad alternate parts with the aim of removing these over-constraints.

40m Lab CAD:
Acquired a stack of original engineering drawings of the vacuum chambers from Steve which I will take home, get scanned, and then use as reference for the cad i'm working on.

Other:
Started paperwork at west bridge office to get paid as an "occasional employee". Hopefully I receive old money.

I've packaged an AP1053 in a Thorlabs box. The gain and the input noise level were measured. It has the gain of ~10 and the input noise of ~0.6nV/rtHz@50MHz~200MHz.

Details

AP1053 was soldered on Thorlabs' PCB EEAPB1 (forgot to take a picture). The corresponding chassis is Thorlabs' EEA17. There is a 0.1uF high-K ceramic cap between DC and GND pins. The power is supplied via a DC feedthru capacitor (Newark / Power Line Filter / 90F2268 / 5500pF) found in the WB EE shop. The power cable has a connector to make the long side of the wires detachable. Because I did not want to leave the RF signal path just mechanically touched, the SMA connectors were soldered to the PCB. As the housing has no access hole, I had to make it at one of the sides.

The gain of the unit was measured using the setup shown in the upper figure of Attachment 2. When the unit was energized, it drew the current of about 0.1A. The measued gain was compensated by the pick off ratio of the coupler (20dB). The gain was measured with the input power of -20, -10, 0, 10, and 15dBm. The measurement  result is shown in Attachment 3. The small signal gain was actually 10dB and showed slight degradation above 100MHz. At the input of 10dB some compression of the gain is already visible. It looks consistent with the specification of +26.0dBm output for 1dB compression above 50MHz and +24.0dBm output below 50MHz.

The noise level was characterized with the setup shown in the bottom figure of Attachment 3. The noise figure of the amplifier is supposed to be 1.5dB above 200MHz and 3.5dB below 200MHz. This is quite low and the output noise of AP1053 can not be measured directly by the analyzer. So, another LN amplifier (ZFL-500HLN) was stacked. The total gain of the system was measured in the same way as above. The measured noise level was ~0.7nV/rtHz between 50MHz and 200MHz. Considering the measurement noise level of the system, it is consistent with the input referred noise of 0.6nV/rtHz. I could not confirm the advertized noise figure of 1.5dB above 200MHz. The noise goes up below 50MHz. But still 2nV/rtHz at 3MHz. I'd say this is a very good performance.

40m Lab Cad:
Updated the dimensions of and fleshed out the chambers in greater detail, by referring to the engineering drawings that Steve gave to me. I have scanned and uploaded most of these drawings to Dropbox in [40mShare]>[40m_cad_models]>[Vacuum Chamber Drawing Scans]. The excel file "LIGO 40m Parts List" in the [40m Lab CAD] folder also lists the Steve drawings I referenced for dimensions of each part.

Next steps:
1. Finish details of all chambers.
2. Start placing representative blocks on the optical table.